Wacha (2-0, 1.89 ERA) has been solid despite having to overcome rain delays in each of his three outings during his first full season in the majors.

"He's strong and he knows what to do out there," manager Mike Matheny said. "He keeps a good focus."

Wacha needed to stay locked in again Sunday in a 6-4 win over the Chicago Cubs. He waited out a 46-minute delay in the third inning before leaving with one out in the seventh, allowing three runs with eight strikeouts for St. Louis (10-6).

"I'm used to it," said Wacha, last year's NL championship series MVP. "You just have to accept it and you've got to stay focused. I tried to stay loose and just keep my mind in what I needed to do."

Wacha was outstanding in his only previous meeting with Washington (9-7) on Sept. 24, taking a no-hit bid into the ninth inning before allowing a single to Ryan Zimmerman with two outs during a 2-0 victory. He won't have to deal with Zimmerman this time after the Nationals third baseman was sidelined by a broken thumb.

St. Louis has won 11 of 13 against Washington, including the five games of the 2012 NL division series. Adam Wainwright continued that mastery Thursday, tossing a two-hitter in an 8-0 win in the opener of this four-game set in the nation's capital.

Matt Holliday doubled for one of his two hits and added two RBIs, while Matt Adams had a single and drove in three runs.

Holliday is 8 for 22 (.364) in six games after batting .216 over the first 10, and the left fielder owns a .361 average over his last 20 regular-season games against the Nats.

Adams has been superb so far with a .355 average, and he's 6 for 15 (.400) while plating four runs in as many games against Washington.

While the Cardinals have won five of six, the Nationals have dropped five of seven.

Washington's chances at turning the tide may not bode well since its batting .153 with 12 runs over the last eight regular-season meetings with St. Louis. The Nats also lead the majors with 20 errors after committing a season-high four Thursday.

"It's not lack of effort. It's not lack of preparation," manager Matt Williams said. "It's not lack of anything."

Bryce Harper is 4 for 24 (.167) in seven games against St. Louis, going 0 for 3 with a strikeout versus Wacha. The 21-year-old left fielder went 0 for 4 on Thursday, ending an eight-game hitting streak during which he batted .483.

Gio Gonzalez (2-1, 3.50) is slated to get the ball for Washington. He allowed two runs in seven innings opposite Wacha on Sept. 24. The left-hander tossed a five-hitter in a 10-0 win in his only regular-season home meeting versus St. Louis on Aug. 31, 2012.

Gonzalez enters this matchup looking to rebound from Sunday's 10-2 loss at Atlanta. He was tagged for six runs and nine hits -- including two homers -- with four walks while hitting a batter in six innings.

That came after he won his first two starts while yielding one run over 12 innings.

Research Notes

Gio Gonzalez dominated hitters with his curveball as he held them to a .312 OPS in 2013 (2nd among lefties). Gonzalez allowed only one home run and had a 72-to-4 strikeout-to-walk ratio in the 158 plate appearances that ended with the pitch. As a team, the Cardinals only had 111 plate appearances end in curveballs from left-handed pitchers, which was 2nd-fewest in the league (0.9 percent walk percentage was last in MLB).